Messages in this thread | | | Date | Thu, 22 Jan 2009 23:03:20 -0500 | From | Mathieu Desnoyers <> | Subject | Re: [ltt-dev] [RFC PATCH] block: Fix bio merge induced high I/O latency |
| |
* KOSAKI Motohiro (kosaki.motohiro@jp.fujitsu.com) wrote: > > So, I ran the tests with my corrected patch, and the results are very > > good ! > > > > "incoming ssh connexion" test > > > > "config 2.6.28 cfq" > > Linux 2.6.28 > > /sys/block/sd{a,b}/device/queue_depth = 31 (default) > > /sys/block/sd{a,b}/queue/iosched/slice_async_rq = 2 (default) > > /sys/block/sd{a,b}/queue/iosched/quantum = 4 (default) > > > > "config 2.6.28.1-patch1" > > Linux 2.6.28.1 > > Corrected cfq patch applied > > echo 1 > /sys/block/sd{a,b}/device/queue_depth > > echo 1 > /sys/block/sd{a,b}/queue/iosched/slice_async_rq > > echo 1 > /sys/block/sd{a,b}/queue/iosched/quantum > > > > On /dev/sda : > > > > I/O scheduler runt-min (msec) runt-max (msec) > > cfq (2.6.28 cfq) 523 6637 > > cfq (2.6.28.1-patch1) 579 2082 > > > > On raid1 : > > > > I/O scheduler runt-min (msec) runt-max (msec) > > cfq (2.6.28 cfq) 523 28216 > > cfq (2.6.28.1-patch1) 517 3086 > > Congraturation. > In university machine room (at least, the university in japan), > parallel ssh workload freqently happend. > > I like this patch :) >
Please see my today's posts with numbers taken after my Seagate firmware upgrade. The runt-max case is pretty hard to trigger "for sure" and I had to do a few runs to trigger the problem. The latest tests are better. E.g. the 3086msec is actually just because the problem has not been hit.
But the echo 1 > /sys/block/sd{a,b}/device/queue_depth echo 1 > /sys/block/sd{a,b}/queue/iosched/slice_async_rq echo 1 > /sys/block/sd{a,b}/queue/iosched/quantum
Are definitely helping a lot, as my last numbers also show. The patch, OTOH, degraded performances rather than making them better.
Mathieu
> > > > > > It looks like we are getting somewhere :) Are there any specific > > queue_depth, slice_async_rq, quantum variations you would like to be > > tested ? > > > > For reference, I attach my ssh-like job file (again) to this mail. > > > > Mathieu > > > > > > [job1] > > rw=write > > size=10240m > > direct=0 > > blocksize=1024k > > > > [global] > > rw=randread > > size=2048k > > filesize=30m > > direct=0 > > bsrange=4k-44k > > > > [file1] > > startdelay=0 > > > > [file2] > > startdelay=4 > > > > [file3] > > startdelay=8 > > > > [file4] > > startdelay=12 > > > > [file5] > > startdelay=16 > > > > [file6] > > startdelay=20 > > > > [file7] > > startdelay=24 > > > > [file8] > > startdelay=28 > > > > [file9] > > startdelay=32 > > > > [file10] > > startdelay=36 > > > > [file11] > > startdelay=40 > > > > [file12] > > startdelay=44 > > > > [file13] > > startdelay=48 > > > > [file14] > > startdelay=52 > > > > [file15] > > startdelay=56 > > > > [file16] > > startdelay=60 > > > > [file17] > > startdelay=64 > > > > [file18] > > startdelay=68 > > > > [file19] > > startdelay=72 > > > > [file20] > > startdelay=76 > > > > [file21] > > startdelay=80 > > > > [file22] > > startdelay=84 > > > > [file23] > > startdelay=88 > > > > [file24] > > startdelay=92 > > > > [file25] > > startdelay=96 > > > > [file26] > > startdelay=100 > > > > [file27] > > startdelay=104 > > > > [file28] > > startdelay=108 > > > > [file29] > > startdelay=112 > > > > [file30] > > startdelay=116 > > > > [file31] > > startdelay=120 > > > > [file32] > > startdelay=124 > > > > [file33] > > startdelay=128 > > > > [file34] > > startdelay=132 > > > > [file35] > > startdelay=134 > > > > [file36] > > startdelay=138 > > > > [file37] > > startdelay=142 > > > > [file38] > > startdelay=146 > > > > [file39] > > startdelay=150 > > > > [file40] > > startdelay=200 > > > > [file41] > > startdelay=260 > > > > -- > > Mathieu Desnoyers > > OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68 > > > > _______________________________________________ > > ltt-dev mailing list > > ltt-dev@lists.casi.polymtl.ca > > http://lists.casi.polymtl.ca/cgi-bin/mailman/listinfo/ltt-dev > > > > > _______________________________________________ > ltt-dev mailing list > ltt-dev@lists.casi.polymtl.ca > http://lists.casi.polymtl.ca/cgi-bin/mailman/listinfo/ltt-dev >
-- Mathieu Desnoyers OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68
| |